Flat ribbon cables, i.e., cables comprising a number of adjacent conductors, are widely used in the data transmission and communication fields to interconnect electronic devices such as communication equipment and computers. In the applications addressed herein the ribbon cable is external to a device housed in an enclosure and extends to connect that device to another or one cable is connected to another intermediate two electronic devices. The cable is terminated at both ends by connectors which mate with counterparts attached to the electronic devices or another cable to provide numerous electrical circuits. Since the cable is exposed, there exists the danger that forces (strain) placed on the cable will pull the cable free of its connector. Many devices have been produced which attach to the device enclosure and clamp the cable to prevent relative movement between the cable and the enclosure so that forces placed on the cable are not transmitted to the interface between the cable and its connector with the possible result of separating the two. Prior devices of this type are known as strain relief devices, or simply strain reliefs, and have generally been successful in preventing separation of the cable and its connector. Unfortunately, these strain reliefs have usually been custom-made for the particular cable to be used. Since ribbon cable is produced in various thicknesses, this approach has required that a large number of strain relief devices be provided and kept in stock to accommodate any of the possible cable thicknesses available.